Resolution:
ERMS with Powerpact P or R breakers is typically ordered in the factory assembled gear. If there are existing breakers without ERMS, adding it in the field CAN be done, but it has to be ordered as many individual parts. Since the gear would have been made without ERMS, there will be no provisions to add it, so it will be totally up to the installer/end-user to determine a suitable and code-compliant place to mount it. If field installation of ERMS is absolutely required, the below picture shows the parts that are needed. Note that this does not allow for additional communication with the trip unit, so it is only ERMS. (Addition of an IFE module would be needed)